On 19 March 2016 at 15:39, Daniel Vetter <daniel@xxxxxxxx> wrote: > On Fri, Mar 18, 2016 at 08:02:39PM +0000, Chris Wilson wrote: >> Drivers, especially i915.ko, can fail during the initial migration of a >> dma-buf for CPU access. However, the error code from the driver was not >> being propagated back to ioctl and so userspace was blissfully ignorant >> of the failure. Rendering corruption ensues. >> >> Whilst fixing the ioctl to return the error code from >> dma_buf_start_cpu_access(), also do the same for >> dma_buf_end_cpu_access(). For most drivers, dma_buf_end_cpu_access() >> cannot fail. i915.ko however, as most drivers would, wants to avoid being >> uninterruptible (as would be required to guarrantee no failure when >> flushing the buffer to the device). As userspace already has to handle >> errors from the SYNC_IOCTL, take advantage of this to be able to restart >> the syscall across signals. >> >> This fixes a coherency issue for i915.ko as well as reducing the >> uninterruptible hold upon its BKL, the struct_mutex. >> >> Fixes commit c11e391da2a8fe973c3c2398452000bed505851e >> Author: Daniel Vetter <daniel.vetter@xxxxxxxx> >> Date: Thu Feb 11 20:04:51 2016 -0200 >> >> dma-buf: Add ioctls to allow userspace to flush >> >> Testcase: igt/gem_concurrent_blit/*dmabuf*interruptible >> Testcase: igt/prime_mmap_coherency/ioctl-errors >> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> >> Cc: Tiago Vignatti <tiago.vignatti@xxxxxxxxx> >> Cc: Stéphane Marchesin <marcheu@xxxxxxxxxxxx> >> Cc: David Herrmann <dh.herrmann@xxxxxxxxx> >> Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx> >> Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx> >> CC: linux-media@xxxxxxxxxxxxxxx >> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx >> Cc: linaro-mm-sig@xxxxxxxxxxxxxxxx >> Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx >> Cc: devel@xxxxxxxxxxxxxxxxxxxx > > Applied to drm-misc, I'll send a pull to Dave the next few days if no one > screams. > -Daniel Thanks for pulling it via drm-misc, Daniel. Chris, I feel since this is an API change, it also needs an update to the Documentation file. With that, and a minor nit below, please feel free to add Acked-by: Sumit Semwal <sumit.semwal@xxxxxxxxxx> > >> --- >> drivers/dma-buf/dma-buf.c | 17 +++++++++++------ >> drivers/gpu/drm/i915/i915_gem_dmabuf.c | 15 +++++---------- >> drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c | 5 +++-- >> drivers/gpu/drm/udl/udl_fb.c | 4 ++-- >> drivers/staging/android/ion/ion.c | 6 ++++-- >> include/linux/dma-buf.h | 6 +++--- >> 6 files changed, 28 insertions(+), 25 deletions(-) >> >> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c >> index 9810d1df0691..774a60f4309a 100644 >> --- a/drivers/dma-buf/dma-buf.c >> +++ b/drivers/dma-buf/dma-buf.c >> @@ -259,6 +259,7 @@ static long dma_buf_ioctl(struct file *file, >> struct dma_buf *dmabuf; >> struct dma_buf_sync sync; >> enum dma_data_direction direction; >> + int ret; >> >> dmabuf = file->private_data; >> >> @@ -285,11 +286,11 @@ static long dma_buf_ioctl(struct file *file, >> } >> >> if (sync.flags & DMA_BUF_SYNC_END) >> - dma_buf_end_cpu_access(dmabuf, direction); >> + ret = dma_buf_end_cpu_access(dmabuf, direction); >> else >> - dma_buf_begin_cpu_access(dmabuf, direction); >> + ret = dma_buf_begin_cpu_access(dmabuf, direction); >> >> - return 0; >> + return ret; >> default: >> return -ENOTTY; >> } >> @@ -613,13 +614,17 @@ EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access); >> * >> * This call must always succeed. >> */ Perhaps update the above comment to reflect the change as well? >> -void dma_buf_end_cpu_access(struct dma_buf *dmabuf, >> - enum dma_data_direction direction) >> +int dma_buf_end_cpu_access(struct dma_buf *dmabuf, >> + enum dma_data_direction direction) >> { >> + int ret = 0; >> + >> WARN_ON(!dmabuf); >> >> if (dmabuf->ops->end_cpu_access) >> - dmabuf->ops->end_cpu_access(dmabuf, direction); >> + ret = dmabuf->ops->end_cpu_access(dmabuf, direction); >> + >> + return ret; >> } << snip>> Best regards, Sumit. -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html